I have a 2 year old Comfortkeeper furnace that recently gave the 3 green light code for a stuck open/closed pressure switch. I went through all the normal checks and then checked the small drain line the goes into the cement floor with a small whole cut just for that drain. I could get it to reset by powering off then on and calling for heat. Originally I could get it to cycle one time then it would throw the code again. Now after picking up that drain I can drain a small amount of water, say 1/4 of a cup or less. When doing so I can reset the furnace and get it to run fine with no code for a few days again and it will then throw the code again. Then I do the same again and it will again work fine for a few days. I am assuming there may be some water or issue in the draft Enducer? If so on a 2year old furnace what could I be looking for outside of checking the Enducer and drainage tubing that what I am doing would have this effect? I have not don't anything internally to the furnace just check vent pipe and that drain for blockage. Any ideas?